Perhaps, and this one is open for debate, the last pulse of refugees are ex-Rim Worlders who flee in that direction and become very much 2nd class citizens, like the Chinese were on the Australian goldfields or quarantined on thier own ghetto world.
Additionally, groups from the LC and FW are taken in, but are also quarantined, but not to the extent of the Rim Worlders.
This adds some heavy social tensions that are not talked about at parties, but are an ever growing issue for the SC, as the late migrant populations are growing at a greater rate than the stable and comfortable established systems.
Perhaps there are the first stirring of thoughts of independence from the SC?